CompatHelper: bump compat for Optimisers to 0.4, (keep existing compat)

[github-actions]

This pull request changes the compat entry for the Optimisers package from 0.3.3 to 0.3.3, 0.4.
This keeps the compat entries for earlier versions.

Note: I have not tested your package with this new compat entry.
It is your responsibility to make sure that your package tests pass before you merge this pull request.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 31.66%. Comparing base (c86580b) to head (b076f82).
Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2520      +/-   ##
==========================================
- Coverage   33.54%   31.66%   -1.88%     
==========================================
  Files          31       31              
  Lines        1911     1923      +12     
==========================================
- Hits          641      609      -32     
- Misses       1270     1314      +44     

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[mcabbott]

Suggested change

	Optimisers = "0.3.3, 0.4"
	Optimisers = "0.4"